Best open-source alternatives to Microsoft Teams

Rocket.Chat is an open-source communications platform aimed at organizations that need secure, customizable collaboration tools. It supports team messaging and real-time conversations for internal coworkers as well as external communication with customers, citizens, or partner companies. The project is designed for self-hosted, cloud, and air-gapped deployments, making it suitable for regulated or high-security environments. It also includes security and governance features such as identity management, end-to-end encryption, and role- and attribute-based access control, while offering extensibility through a marketplace, Apps-Engine, and external integrations.

Neko is a self-hosted virtual browser and desktop streaming project designed to run inside Docker and deliver the session to users over WebRTC. It is aimed at people who want a private, secure, and shareable browser environment, including developers, teams, presenters, and users who need a persistent or isolated browsing session. The project emphasizes collaborative use: multiple participants can access the same session, interact with the browser in real time, and use it for watch parties, teaching, support, brainstorming, or remote presentations. Beyond browsers, it can stream other Linux applications or even a full desktop environment, and it also supports use cases like session broadcasting, recording, and browser automation.

Zulip is an open-source team chat platform designed to help organizations manage both real-time and asynchronous communication in a more structured way than traditional chat apps. Its signature feature is topic-based threading, which keeps conversations organized and makes it easier for distributed teams to follow multiple discussions without losing context. The project is aimed at teams, open-source communities, and other organizations that need productive group communication. The README highlights self-hosting on Ubuntu or Debian Linux, deployment via Docker, and hosted cloud options through Zulip Cloud. It also emphasizes a large contributor community and extensive documentation for both code and non-code contributions, suggesting a mature project with a broad user and developer ecosystem.

The Lounge is a self-hosted web IRC client intended for people who want a persistent, browser-based way to stay connected to IRC networks. It is positioned as a modern alternative to traditional IRC clients, with features such as push notifications, link previews, and message markers to make IRC feel more contemporary. It is aimed at users who want their IRC presence to persist across devices and sessions. The README emphasizes that it stays connected while the user is offline, works across platforms wherever Node.js runs, and provides a responsive interface for desktop, smartphone, and tablet use. The project also documents a source-based installation path for development and links to a Docker-based deployment option for stable releases.

Mattermost is an open core collaboration platform designed for teams that want to self-host their communication and workflow stack. It provides a web-based interface and native clients for desktop and mobile, and is positioned for use cases such as DevSecOps, incident resolution, and IT service desk operations. The project is the primary source for core platform development and is implemented in Go and React. The software runs as a single Linux binary and depends on PostgreSQL for storage. The README emphasizes deployment flexibility, with installation paths for Docker, Ubuntu, tar archives, Kubernetes, and Helm. It also points users to product and developer documentation, and highlights a broad integration surface including webhooks, slash commands, drivers, web services, apps, and plugins.

Tinode is an instant messaging platform intended as a modern, open replacement for XMPP-style federated chat systems. It provides a backend written in Go and clients for web, Android, iOS, and a scriptable command-line interface. The project is aimed at teams or individuals who want a self-hostable messaging stack with mobile and browser access. The server supports messaging, calls, channels, access control, and multi-device synchronization, while also offering administration tooling and support for custom authentication backends. It can be deployed with different database backends and uses JSON/websocket or protobuf/gRPC transports. The README also points to public demo and sandbox services for trying the system before self-hosting.

MiroTalk P2P is an open-source, self-hosted video conferencing platform built around direct WebRTC peer-to-peer connections. It is designed for people or organizations that want to run their own real-time communication system with control over data, privacy, and deployment. The project emphasizes quick self-hosting, offering both a manual Node.js setup and Docker-based deployment. Its feature set includes high-resolution video, screen sharing, chat, recording, whiteboards, file sharing, and integration options such as a REST API, embeddable widgets, and messaging service hooks. The README also highlights OIDC authentication, room passwords, host protection, and white-label/rebranding support, suggesting it is aimed at customizable production use as well as demonstrations and internal collaboration.

screego/server is a screen-sharing service aimed at developers who need clearer, faster remote viewing than typical corporate meeting tools provide. It is positioned as a lightweight addition to existing collaboration software, focused specifically on screen sharing rather than broader conferencing or chat features. The project emphasizes simple deployment and practical network handling. The README highlights support for multi-user screensharing, secure transfer over WebRTC, low latency, high resolution, and an integrated TURN server for NAT traversal. It can be installed either with Docker or as a single binary, and the project provides a public demo instance and documentation for setup and configuration.

Ergo is a self-hosted IRC server designed for operators who want a modern, highly configurable network with built-in services. It combines core IRC daemon functionality with account management, channel registration, and bouncer-like behavior, making it useful for communities that want persistent identities and message history without stitching together separate components. The project emphasizes ease of setup, IRCv3 compatibility, and runtime reconfiguration through a reloadable YAML config. It can be downloaded as a release, built from source, or deployed with Docker, and it also supports platform packages for some Linux distributions. Documentation is split between an end-user guide and an operator manual, and the README points to a public test network for trying the server in action.

Openfire is an open-source XMPP server aimed at real-time collaboration and instant messaging. It is part of the Ignite Realtime community and is described as easy to set up and administer while emphasizing security and performance. The project is intended for organizations and developers who need a standards-based messaging backend built on the widely adopted XMPP protocol. The README highlights a Maven-based build, modular project structure, plugins, and platform-specific installers, along with instructions for launching the server from the command line after building. It also points to documentation, community support, bug tracking, nightly builds, and translations.

MiroTalk SFU is a self-hosted WebRTC video conferencing platform designed for real-time communication, collaboration, and live streaming. It positions itself as an open-source alternative to services like Zoom, Google Meet, Jitsi Meet, and Microsoft Teams, with an emphasis on privacy, full data control, and no vendor lock-in. The project is aimed at teams and organizations that want to run their own conferencing infrastructure. It uses a scalable SFU architecture powered by mediasoup, and the README highlights features such as high-resolution video, screen sharing, recording, chat, whiteboarding, file sharing, OIDC authentication, room protections, integrations, and a full REST API for external use.

Converse is a browser-based XMPP chat application designed for people who want a modern messaging client that can be used either as a standalone web app or embedded into an existing website. It is explicitly client-side, meaning the user interface runs in the browser rather than as a traditional server-side web application. The project targets deployments that need flexible presentation options and deep integration with XMPP servers and web platforms. It supports multiple display modes, rich chat features such as message reactions and styling, OMEMO end-to-end encryption, file sharing, and anonymous login where the server allows it. The README also highlights plugin extensibility, broad XMPP protocol support, and integrations with servers like Prosody, ejabberd, and Openfire as well as platforms such as WordPress and Roundcube.

Campfire is a web-based chat application intended for self-hosting. It is presented as a collaborative messaging tool for teams or groups that need rooms, direct messaging, file sharing, and searchable conversation history in one place. The README emphasizes that it can be deployed as a single-machine instance with all required components bundled together. The project appears designed for operators who want a relatively turnkey self-hosted chat system. Deployment is supported through ONCE, which can guide setup and keep the instance updated automatically, or by running the Docker image directly. The README also notes an admin-account setup wizard on first launch and an API intended for bot integrations, suggesting it can fit into automated workflows as well as human chat use.

InspIRCd is an Internet Relay Chat server aimed at users who need a self-hosted, high-performance IRCv3 service. It supports UNIX-like systems and Windows, and the README emphasizes that the project is actively developed, with the master branch considered unstable for production use. The project is built from source on most UNIX-like platforms, with documentation provided for source installation on both UNIX-like systems and Windows. It also offers binary packages for some operating systems and a Docker image. Additional modules can be enabled during builds, and the project provides official documentation, support resources, and a test network for experimentation.

Tuwunel is a Matrix homeserver implementation aimed at organizations and self-hosters that need a scalable alternative to Synapse. It is written entirely in Rust and is described as low-cost, enterprise-ready, and community-driven while implementing the Matrix specification for almost all use cases. The project positions itself as the official successor to conduwuit. The README emphasizes practical deployment paths rather than a hosted service. Users can install it via source, static binaries, Debian/RPM packages, Arch, Nix, Alpine, or Docker, then configure a server name and database path before starting the server. It can run with or without a reverse proxy, though Caddy is recommended for automated TLS. The first user to register becomes server admin, and the project provides migration guidance for existing conduwuit deployments.

Galene is a videoconferencing system aimed at self-hosters and administrators who want a lightweight, easy-to-deploy conferencing platform. The README presents it as a web-based system that can be started locally after building from source, then accessed in a browser at a local HTTPS URL. The project includes documentation for installation, usage, administration, client development, and the client protocol, suggesting it is intended not only for end users but also for operators and integrators. The README also references an administrative API, which indicates support for programmatic management. It appears to use groups and local user credentials for access to meetings, and the example startup flow shows how a server can be run with a small amount of setup.

ejabberd is an open-source realtime communications platform built on Erlang/OTP. It is designed for administrators and organizations that need a scalable backend for messaging and related network services, and it bundles an XMPP server together with MQTT broker and SIP service functionality. The project can be installed from source, via operating-system packages, through Homebrew, or by using published Docker container images and release installers. Its README points users to the ejabberd documentation site for setup and administration guidance, and to separate developer documentation for contributors. The project also notes a commercial offering and support path through ProcessOne, including a Business Edition and cloud-hosted service.

This project is the Android client for Delta Chat, a messaging application. It is intended for users who want to use Delta Chat on Android devices, with distribution through Google Play and F-Droid as well as other platform downloads from the Delta Chat website. The repository points contributors to separate build and contribution documentation, and it references a shared Chatmail core library for core functionality and general project information. The README also indicates that app metadata, changelogs, app strings, and the website are maintained through translation platforms, suggesting an actively localized mobile client rather than a standalone utility.

Plug-N-Meet is an open-source web conferencing platform aimed at teams and developers who want to embed a customizable, self-hosted meeting experience into existing websites or applications. It is built on LiveKit and presented as a scalable system with a Go backend, a React/Redux client, and a separate recorder component for handling recordings and broadcasting. The project focuses on rich meeting functionality and integration. It supports audio and video calls, screen sharing, collaborative whiteboarding, polls, breakout rooms, and AI-assisted meeting intelligence such as live transcription, translations, and summaries. It also provides APIs, SDKs, and plugins for common platforms like WordPress, Moodle, and Joomla, making it suitable for organizations building branded conferencing experiences or adding conferencing to LMS and CMS deployments.

Chatto is a self-hostable chat application aimed at teams and communities. The repository packages several components together: the main chat server, a CLI, a bundled web frontend, an identity provider, and supporting framework modules. The README positions it as easy to run locally and suitable for development or self-hosted deployments, with cloud hosting planned for later. The project also includes adjacent tooling for workflows and identity, showing that it is more than a simple chat UI. Development is driven through the `mise` tool, which installs dependencies and starts the application stack, and a fuller development mode can bring up supporting services like Authling, Runling, Mailpit, and LiveKit. The README also documents a default development login, indicating a multi-user product with authentication. The codebase uses a mixed licensing model, with the core Chatto software under AGPL and some modules under Apache-2.0 or MIT.

Snikket is a self-hosted personal messaging service aimed at people who want an open-source alternative to proprietary, centralized chat platforms. The repository described here provides the source used to build Snikket server Docker images, rather than the end-user application itself. The README focuses on installation and image-building workflows. It points users to the Snikket installation guide for setup, and it documents how to build images with GNU make and run them using docker compose after editing a configuration file. The project is positioned as easy to use while still supporting the expected features of a modern messaging service.

SAMA is a chat server and messaging protocol project intended to serve as an alternative to XMPP. It is aimed at developers building messaging products and at users of the associated client applications, including a web frontend and a Flutter mobile client. The repository describes the server as part of a broader SAMA stack powered by uWebSockets.js, with infrastructure centered on Node.js, MongoDB, Redis, and AWS. Deployment and development guidance points to Docker-based setup documentation, and the README highlights a public cloud demo that can be used to try the full stack. The project also exposes documented APIs for common messaging functions such as users, conversations, messages, activities, address book, and push notifications.

UnrealIRCd is an open source IRC server intended for running public or private IRC networks. It has been maintained since 1999 and is positioned as a mature, widely deployed daemon with a strong emphasis on modularity, security, and deep configuration control. The project is aimed at administrators who need a feature-rich IRC server rather than a lightweight chat client. Its README highlights support for modern IRC capabilities such as IRCv3, TLS, cloaking, JSON-RPC, anti-flood and anti-spam protections, GeoIP, and remote includes. Installation is documented for source builds on Unix-like systems and for Windows, and the project maintains extensive online documentation, FAQs, and support channels for operators.

Apache OpenMeetings is an Apache-hosted web conferencing and groupware application for organizations that need online meetings, chat, collaborative whiteboarding, and shared document editing. It is positioned as a broad collaboration server rather than a narrow meeting tool, with functionality spanning room-based communication, moderation, and related office-style workflows. The README shows that the project is built from source with Maven and run on Java 21, and that it depends on Kurento for media remoting and streaming. It also points readers to the project website for installation, upgrades, build instructions, and release notes. The release history suggests a mature product with ongoing security updates, mobile improvements, OpenAPI-based integration support, and features such as WebRTC audio/video/screen sharing and two-factor authentication.

ngIRCd is a lightweight IRC daemon intended for small or private networks. It is written in C, distributed under the GNU GPL, and aims to provide a simple, portable server that is easy to configure and maintain. The project supports both standalone operation and participation in a larger IRC network, including deployments across a LAN or the internet. It is aimed at administrators who need a straightforward IRC service with common protocol features such as IPv6, SSL/TLS, PAM-based authentication, user cloaking, and compatibility with a broad range of platforms.

ClickClack is a self-hostable chat system designed for teams that want one platform for people, bots, and agents. It bundles a Go backend, a Svelte web frontend, a CLI, and a TypeScript SDK behind an API-first architecture, making it suitable for both interactive chat use and programmatic integrations. The project is aimed at self-hosters and developers who need a chat service they can deploy themselves, extend, and automate. The README highlights web and desktop clients for day-to-day use, plus REST and WebSocket access for external clients, bots, and custom tooling. Deployment options include release binaries, Docker, and source builds, with documentation covering authentication, storage, backups, and production configuration.

Quassel IRC is a cross-platform IRC client designed around a distributed architecture. Instead of running as a traditional single-process chat app, it uses a central core that one or more clients can connect to and disconnect from, allowing users to stay connected to IRC sessions while switching devices or interfaces. The project is intended for users who want a comfortable graphical IRC experience on major platforms, while also benefiting from a persistent core-side connection model. The README points users to official downloads, nightly builds, and the project wiki for setup and deeper documentation. It also notes that the core can create its database and initial admin user on first run, and that additional users and password changes are managed through the core command-line tool.

Kiwi IRC is a browser-based IRC messenger aimed at people who want a flexible client that can be hosted like a static website. It is positioned for individual users, single networks, bouncer setups, and workplace team use, with support for both direct IRC connections and proxy-based setups. The project emphasizes customization and lightweight deployment: it can be served from static files, configured at runtime with a single JSON file, and extended through plugins. The README describes support for multiple layouts, themes, desktop notifications, and features such as file uploading and video calling through plugins. It is intended for modern browsers and can be built or developed locally with Node.js and yarn.

Tigase XMPP Server is a Java-based XMPP/Jabber server designed for deployments that need a modular, standards-compliant messaging backend. It targets administrators and organizations that want to run their own XMPP infrastructure with support for client, server-to-server, and component connections. The project emphasizes protocol coverage and extensibility. The README highlights support for XMPP over TCP, BOSH, and WebSockets, plus features such as service discovery, multi-user chat, publish-subscribe, message archiving, stream management, and push notifications. It also includes an HTTP API for integrating with systems that do not speak XMPP directly. The repository provides source code for the core server, while related Tigase projects add optional components, tools, clients, and IoT integrations.

A project with documentation available at robustirc.net/docs.